1. Field of the Invention
The invention relates to a highly-productive manufacturing method for a sulfide-based solid electrolyte material.
2. Description of Related Art
With a rapid proliferation of information-related equipment and communication equipment, such as personal computers, camcorders and cellular phones, in recent years, it becomes important to develop a battery used as a power supply of the information-related equipment or the communication equipment. In addition, in automobile industry, or the like, development of a high-power and high-capacity battery for electric vehicles or hybrid vehicles has been proceeding. Currently, among various types of battery, a lithium secondary battery becomes a focus of attention in terms of high energy density.
Currently commercially available lithium secondary batteries employ an electrolytic solution that contains a flammable organic solvent. Therefore, it is necessary to install a safety device that suppresses an increase in temperature in the event of a short circuit or improve a structure or a material for short-circuit prevention. In contrast to this, lithium secondary batteries in which an electrolytic solution is replaced with a solid electrolyte layer do not use a flammable organic solvent in the batteries. For this reason, it is considered that the safety devices for the lithium secondary batteries are simplified and the lithium secondary batteries are excellent in manufacturing cost and productivity. Furthermore, a sulfide-based solid electrolyte material is known as a solid electrolyte material that is used for the solid electrolyte layer.
The sulfide-based solid electrolyte material has a high lithium ion conductivity, so it is useful to obtain a high-power battery. Therefore, various researches have been carried out so far. For example, Japanese Patent Application Publication No. 2013-16423 (JP 2013-16423 A) describes an Li2S—P2S5—LiI-series sulfide-based solid electrolyte material.
On the other hand, Japanese Patent Application Publication No. 7-242414 (JP 7-242414 A) describes a method of synthesizing an alkali metal iodide (NaI, KI) in an aqueous solution by using iodine and an organic reductant.
For example, when the sulfide-based solid electrolyte material is synthesized by using Li2S, P2S5 and LiX (X is one of F, Cl, Br and I), Li2S, P2S5 and LiX have been separately prepared and then synthesized with one another so far. With such a manufacturing method, there is an inconvenience that the productivity of a sulfide-based solid electrolyte material is low.